I do like how creative some people's list of snakes are. Also, the gaboon viper that Greg mentioned, very beautiful snake and very deadly.
While I like the venomous snakes I'm just to much of a chicken to ever consider keeping them. If I could find a adult green tree python that was completely yellow. As majority of you know they all start out yellow or reddish, but as they age they go through there color change and turn green. While there is a few of them out there that retain a lot of there yellow through out the years there isn't very many.